Mariner 75hp 89 model

[1wahu]

Hi new to boating and to the forum i have a loud constant beep coming from my motor after about 10 minutes of driving the boat it seems fine when at idle it only happens when moving i have water flow plenty of oil thought it may be a impeller problem any thoughts

 

[Texasmark]

Re: Mariner 75hp 89 model

Constant beep is overtemp.

Thermostat is probably stuck closed.

Engine has a poppet/popoff/pressure relief that opens at higher rpm's or when boat is in motion and ram water is forced into water inlets which bypasses the t-stat and provides cooling which turns off the "buzzard". BTDT

They're about $8 and you can buy them on here.

Mark

 

[Vlad D Impeller]

Re: Mariner 75hp 89 model

I have the same year and model motor, start your daignostics from the water pump then move on to the t-stat and poppet valve, be sure that there are no blockages in the water passages.
If you have'nt a repair manual get one you'll need it, you can order one right here at iboats.

 

[1wahu]

Re: Mariner 75hp 89 model

Constant beep is overtemp.

Thermostat is probably stuck closed.

Engine has a poppet/popoff/pressure relief that opens at higher rpm's or when boat is in motion and ram water is forced into water inlets which bypasses the t-stat and provides cooling which turns off the "buzzard". BTDT

They're about $8 and you can buy them on here.

Mark

 

[1wahu]

Re: Mariner 75hp 89 model

Thanks something to look at might just replace t-stat probably due for an impeller as well is the poppet pressure relief part of the t-stat or seperate can't find for sale on here

Dan

 

[Texasmark]

Re: Mariner 75hp 89 model

Poppet on mine ('02 90 hp 3 cyl) is next to the stat. One cover covers both of them. Standing behind he engine the cover is sitting on top of the water jacket that covers the entire rear of the powerhead. Real easy to tell what it is. The hole in the poppet is maybe 4 x the area of the stat.

Personally, with your symptons, I'd leave the poppet alone. Seems to be doing it's job.

If, at a later date it fails, you can worry about it then. If it fails on you while out on the water, you can get home by running slowly.......cooling the engine from the tstat opening.

I didn't even buy a new gasket for the cover. Prised it off carefully and put it back on with blue RTV. No problem.